There will be no chance of the government keeping people following advice if restrictions are lifted for people who have been vaccinated before they are lifted for those who have not yet been offered the vaccine. That is one of the main reasons the effectiveness of vaccination in reducing transmission will not be published yet - the data was generated as far back as September (in the same studies which validated the percentage effectiveness of the vaccine). You can potentially infer that vaccination -does- significantly reduce the incidence of transmission, since if it did not, there would be no reason to delay publication of this information, but that is speculative.
There are four key factors at work here:
1. Rate of vaccination - that is now in the region of 2million people per week so you would reach full vaccination in approximately another 25 weeks.
2. Availability of vaccine - that could become a limiting factor on achieving the above.
3. The rates of hospitalisation and death. In government terms, higher levels of infection which are asymptomatic or mild enough that people remain at home do not matter. It is only overwhelming the NHS or high levels of death which are regarded as politically unacceptable.
4. More effective treatments becoming available. This is happening in parallel with vaccine development - if this significantly reduces the number of people who need hospital treatment or die then the infection rate can rise.
The COVID impact on the one hand is weighed against other short-term impacts on the other, including the economic impact and the rate of death above the baseline from other causes including suicide, domestic violence, heart-attacks and strokes; together with a minor weighting for reduced life expectancy due to other effects such as increased obesity and delayed diagnosis (the total number of life-years which are projected to be lost to the three main cancers due to delayed diagnosis already hugely outstrips the total deaths from COVID, but these deaths will not occur all at once so are deemed more acceptable).
Throw that lot into the mix and you get out a view on what is/is not acceptable to the government for people to do as a progression over time. It is very difficult to predict, but if I had to hazard a guess I would suggest there will be re-opening of schools in the second week of March and if, as anticipated, this does not result in much of a rise (mainly because it has probably already gone round most schoolchildren and their families), opening of non-essential retail around late March.
Social activity such as pubs/restaurants may well open around the same time, but there is likely to be a big change. One of the huge fights which is coming is over asymptomatic testing. Currently, it looks like it would be difficult to force an employee, or anyone who is legally obliged to be in a particular place, to have a test. It would need a change in the law to do it, but it looks like things are gearing up to test that principle in schools and workplaces. However, anywhere where it is optional to be, a test could be made obligatory to enter and that would include pubs and restaurants. This is likely to be played out against a timeframe in which rates are falling (more people have been vaccinated and the weather is warmer anyway) so it could be difficult to force through.
Given this potential sticking point, and that the government would clearly prefer to keep things locked down during periods where greater numbers of people than normal may meet socially, I would suggest that social interaction of some form may resume after Easter (another two months from now) and that somewhere around May/June is the likely point where a small group of people from different households may be allowed to meet, but if that involves anything like a pub or a restaurant they need to be a position where they can afford to risk taking a test.
Some form of structured return to something that may resemble 'normal' in some aspects (e.g. able to visit relatives under some circumstances, or meet friends indoors) looks like it may start to be possible from around September, although a new rise/new variant may well put paid to that again by October/November. It looks likely that next winter will have less impact and hence the lockdown will be shorter and maybe less severe, with a possible relaxation of some rules, like being able to go on holiday, visit friends relatively freely etc. in summer 2022. Whether entering a building without a facemask will ever be allowed again is more debatable - there are some in authority who feel this should be enshrined permanently in law to reduce the spread of other potential diseases.
There are too many factors to call this one. Relating back to the original topic, it is worth noting that you are currently allowed to go shopping and are not obliged to always visit the same shop just because it is the closest, or to follow the same route, so long as the route you take is reasonable. There could be some nicer, more scenic routes to and from some different shops in some other towns in the same general area, which would still be within the principle.
Alec